Electric pull switch mechanism



Jufiy 2B, WM. w. c. TREGONING 11535159372 ELECTRIC PULL SWITCH MECHANISM Filed Dec. 21, 1929 ateaatetl duty 23, 1931 D ESTATES WILL C. TREGONIN G, OF MILWAUKEE, WISCONSIN, ASSIGNOR 'IO CUTLER-HAMMER, INCL, OF MILWAUKEE, WISCONSIN, A CORPORATION OF DELAWARE ELECTRIC PULL SWITCH MECHANISM Application filed December 21, 1929. Serial No. 415,853.

This invention relates to improvements in electric pull switch mechanism, and the invention further relates to improvements in electric lamp sockets having my novel switch mechanism applied thereto.

An object of the invention is to provide an improved switch mechanism having a relatively small number ofparts which are of inex iensive construction and which may be readily and inexpensively assembled.

Another object is to provide a switch mechanism the parts of which are of extremely sturdy construction and which is trustworthy in operation.

Another object is to so construct and arrange the parts of the switch mechanism as to insure against fouling of the operatlng chain with respect thereto.

Another object is to provide a novel form of insulating supporting base for the switch mechanism.

Another object is to provide novel means for assembly of a lamp socket with respect to the switch mechanism, and to provide a novel form of support for the device as a whole.

Other objects and advantages of the invention will hereinafter appear.

The accompanying drawings illustrate an embodiment of the invention which will now be described, it being understood that the invention is susceptible of embodiment in other forms without departing from the scope of the appended claims.

In the drawings, Figure 1 is a side elevation of a combined lamp socket and pull switch mechanism constructed in accordance with my invention,the cylindrical enclosing shell or tube being shown in section.

Fig. 2 is a vertical sectional view, looking in the direction of Fig. 1,and certain of the parts being shown in elevation.

Fig. 3 is a vertical sectional view in a plane at right angles to Fig. 2,certain of the switch parts being shown in elevation.

Fig. 4 is a perspective view, in separated relation, of the several parts of the lamp socket and switch mechanism illustrated in Figs. 1, 2 and 3.

Fig. 5 is a side elevation, on a reduced scale, looking in a direction opposite to that of Fig. 1,the enclosing tube being omitted.

Fig. 6 is a perspective view of one of the switch contacts and the clamping element therefor.

Fig. 7 is a similar view of the other switch contact and the combined clamping and terminal element therefor, and

Fig. 8 is a bottom plan View of the insulating block or carrier for the movable contactoi of the switch.

Referring to the drawings, the numeral 15 designates in general the one-piece molded insulating base of the switch, said base having end portions 16 and 17 of approximately cylindrical contour and a relatively shallow intermediate portion 18 of substantially segmental form in cross section. Formed within said intermediate portion 18 is a cylindrical recess 19, and formed integrally with the base and surrounding said recess are two pairs of diametrically opposed ratchet teeth 20, 21 and 22, 23,-the high ends of said ratchet teeth as shown projecting above the'flat face 24 of portion 18.

Opening onto the base or lower end of ratchet tooth 20 is a recess 25 within which the shank portion 26 of the segmental contact 27 is adapted to fit,the under surface of end portion 16 being recessed as indicated at 28 to accommodate the perforated plate portion 29 which is integral with portion 26 and bent at right angles thereto. Also seated within the recess 28 and adapted for clamping engagement with portion 29 is a metal piece or plate 30 having a tapped opening 81 for cooperation with the shank of a screw 32, as hereinafter more fully described. As shown the contact 27 is inclined at an angle corresponding with the angle of tooth 20. Integral with plate 30 and bent downwardly at switch is adapted to seat,-a perforated metal piece or plate 38 being also seated within said recess and held in clampingengagement with portion 36 and the insulating base, by means of an eyelet 39 or the like (Figs. 2, 3 and .7); the outer end of said eyelet being preferably located Within a countersink 40 in the outer surface of the base. The contact 37 is likewise inclined at an angle corresponding to the angle of tooth 21; the free ends of contacts 27 and 37 preferably extending slightly beyond the ends of their respective ratchet teeth. Plate 38 is provided with an integral angularly extending wiring termi nal portion 41, said portion being tapped to receive a binding screw 42.

Superimposed upon the end portion 16 of the base is the screw shell contact 43 of the lamp socket,the base flange 44 of said screw shell being provided with a relatively wide diametrical slot 45 having an enlargement 46 to permit insertion of a one-piece metal member having a forked portion 47 for clamping engagement with the flange 44 of the screw shell and a wiring terminal portion 48 having a tapped opening to receive the binding screw 49.

Also seated within the screw shell and overlying the forked portion 47 is a perforated insulating disk or washer 50. Superimposed upon disk 50 is a perforated metal disk 51, which is preferably provided with a downwardly angled flange 52 to seat within the perforation in disk 50, said flange in turn providing a seat for flush reception of the countersink head of screw 32. As best shown in Figs. 2 and 3, the metal disk 51 is slightly bulged upwardly toward the center, or of somewhat frusto-conical shape, 'to insure proper functioning of the screw head as the center contact of the socket.

As shown the screw 32 penetrates all of the aforementioned parts of the lamp socket, and passes through a perforation 53 in the end portion 16 of the base, whereupon it is threaded into the perforation 31 in plate 30 to secure all of said part-s to each other and to the end portion 16 of the base. End portion 16 is provided with a cut away portion or recess 54 to accommodate the wiring terminal portion-48.

The movable contactor of the switch pref.- erably comprises a suitable length 55 of a rod or wire of circular cross section,-said contactor being preferably composed of brass and having an enlargement 56 swaged or otherwise formed intermediate the ends thereof. Contactor 55 as shown is of a length trally 'opposed pairs of inclined notches or ratchet teeth 60, 61 and 62, 63,-it being noted that said notches are inclined in a common direction circumferentially of the block, and that the vertical end walls of the opposed notches 60 and 61 are in alinement with the longitudinal center line of slot 58.

Integral with block 57 and projecting cenrom the upper end thereof is a spindle 64. Rotatable and slidable on said spindle is a metal plate 65, said plate having a plurality of integral inclined lugs 66 struck downwardly therefrom and adapted for driving engagement with a corresponding number of the notches 60 to 63 upon rotation of said plate in one direction. Also as will be apparent, said lugs 66 are adapted to ride out of engagement with one group of said notches and into engagement with a successive group of notches upon rotation of plate in the reverse (lirecti0n,or in other words to ratchet around said block.

Plate 65 is provided with a forked lug 67 bent upwardly therefrom at right angles and in a plane radial to the center of said plate,

the end of said lug being bent or curved in the manner illustrated to provide a catch for the end ball of a pull chain 68. Also bent upwardly from plate 65 at right angles and in a plane tangential thereto is a lug 69 the end of which is bent outwardly in a plane parallel to the plate to provide a guide rail for the pull chain 68.

Superimposed upon plate 65 and adapted to bias the same into engagement with the upper end of block 57 is a spring 70 surrounding the spindle 64, one angularly extending end 71 of said spring being adapted for engagement with the l-ug. 6 7 to bias plate 65 to one extreme position. The

other angularly extending end 72 of said spring is adapted for engagement with the lug 73 which is struck downwardly from a plate 74 which is also rotatable and slidable with respect to spindle 64. Struck upwardly from plate 74 are a plurality of equally spaced lugs 75, any one diametrically opposed pair of said lugs being adapted for engagement with the edges 76 and 77 of an insulating plate or strip 78 and another diametrically opposed pair of said lugs being adapted for engagement with the wall of perforations 79 and 80 in said plate. ()bviously by manually pressing plate 74 inwardly to effect disengagement of lugs 75 from the plate or strip 7 8. the plate 74 may be turned in either direction upon the spindle 64 to adjust the tension of spring 70 as desired,-the lugs 75 on plate 74 being then permitted to re-engage the cooperating portions of stri 78 to maintain the tension adjustment so e ected.

The upper end 81 of plate 78 is preferably of reduced width to fit within a correspondingly shaped recess 82 in the upper end portion 16 of the base; and the lower end 83 of said plate is likewise of reduced width to fit within a recess 84 in the lower end portion 17 of the base. Plate 78 is further provided adjacent to the upper end thereof with a perforation 85 which registers with the tapped opening 34 in end portion 33 of plate 30, a screw 86 being adapted to take into said tapped opening 34 to secure the upper end of plate 78 to portion 33.

The, lowerend portion 17 of the insulating base 15 is adapted to fit within a cup-shaped or cylindrical support 87 ,-said support being sheared or slit, as indicated at 88 to provide for inward bending or ofisetting of the portion 89 to clamp the end portion 83 of plate 78 within the recess 84, the lower edge of portion 89 being adapted to engage the horizontal wall of said recess to assist in retaining the insulating base Within the sup: port.-

Base 15 is provided at the rear side thereof (see Fig. 5) with depressions or recesses 90 and 91, and support 87 is provided with slits 92 and 93 to facilitate inward offsetting of the portions 94 and 95 into said recesses and into engagement with the horizontal walls of the latter. This arrangement provides a rigid connection between the insulating base and its support 87 ,the latter preferably having an internally threaded bushing 96 secured thereto in a well known manner.

The base or flange 97 of support 87 is provided with a perforation 98 which is surrounded by an upwardly extending flange to guide the pull chain 68, said pull chain having split washers 99 and' 100 or the like fixed thereto at the points illustrated to thereby limit the degree of movement of the actuating ratchet plate in each direction. As shown the end portion 17 of the base is provided with a cut away port-ion or recess 101 to provide clearance for the pull chain.

Flange 97 of support 87 is further provided with diametrically opposed perforations 102 and 103 to provide for passage of the lead wires (not shown) to the respective terminals 41 and 48, the base 15 being recessed as shown at 104 and 105 to provide clearance for such wires.

As will be understood the stops 99 and 100 are so arranged as to insure only a quarter turn of the contactor 55 upon each successive downward movement of the pull chain, whereby the circuit is alternately completed and interrupted.

Also it will be noted that the end 71 of spring is interposed between the plate 65 and the pull chain, thus insuring agamst any possible derangement of the spring.

As shown it is necessary for the screw 32 and eyelet 39 to penetrate the base 15 in planes at right angles to each other; and in order to provide for formation of base 15 by a straight line molding operation I prefer to form the passage or perforation 53 for screw 32 by molding a slot 106 which extends radially inwardly from the periphery of the end portion 16 of the base to the center thereof, said slot being located at the junction of end portion 16 with the intermediate portion 18 of the base. The other recesses and passages aforedescribed are likewise so shaped and arranged as to permit such straight line molding of the insulating base.

slide over the base 15,the lower edge of said tube being adapted to rest'upon the upper edge of the cup-shaped support 87 (see Figs. 1, 2 and 3).

An insulating rib or wall 108 may be provided to increase the strength and rigidity of the intermediate portion of the base, and

to counteract any tendency toward warping of the molded piece.

What I claim as new and desire to secure by Letters Patent is:

1. In an electric snap switch, in combination, a molded insulating block of substam tially cylindrical contour, said block having a diametrical open slot extending inwardy from one end thereof, said slot having an enlarged portion intermediate the ends thereof, a contactor seated within said slot and having opposite end portions projecting from said block, said contactor having an enlargement to seat within the enlarged portion of said slot to restrain the former against endwise displacement, the other end of said block having a plurality of notches arranged in diametrically opposed pairs, the bottom walls of said notches being inclined in a common direction circumferentially of said block, the vertical end walls of one pair of notches being alined with the longitudinal center line of said slot, a concentric spindle integral with said block and extending from the last mentioned end thereof, a ratchet plate rotatable on said spindle, said plate having integral inclined lugs adapted to jointly engage the end walls of said notches upon rotation of said plate in one direction and to ride out of-said notches upon rotation of said plate in the opposite direction, and means for effecting rotation of said plate in said directions alternately.

'2. In an electric snap switch, in combination, a molded insulating block of substantially cylindrical contour, said block having a diametrical open slot extending inwardly from one end thereof, said slot having an enlarged portion intermediate the ends thereof, a contactor seated within said slot and having opposite end portions projecting from said block, said contactor having an enlargement to seat within the enlarged portion of said slot to restrain the former against endwise displacement, the other end of said bloclr having a plurality of notches arranged in diametrically opposed pairs, the bottom walls of said notches being inclined in a common-d1- rection circumferentially of said block, the vertical end walls of one pair of notches being alined with the longitudinal center line of said slot, a concentric spindle integral with said block and extending from the last mentioned end thereof, a ratchet plate rotatable on said spindle, said plate having integral inclined lugs adapted to jointly engage the end walls of said notches upon rotation of said plate in one direction and to ride out of said notches upon rotation of said plate in the opposite direction, means for. effecting rota tion of said plate in said directions alternately, said means including a pull chain attached to said plate to efiect rotation thereof in the first mentioned direction, a coiled torsion spring having one end in engagement with said plate to bias the latter in the oppo-' site direction, an adjusting plate slidably mounted on said spindle and having an inwardly extending lug with which the other end of said spring is adapted to engage, said adjusting plate also having a plurality of outwardly extending lugs, and a bearing plate for said spindle, said bearing plate having shoulders with which saidlast mentioned lugs are adapted to engage.

3. In a rotary pull switch; in combination, a one-piece molded insulating base having approximately cylindrical end portlons and a relatively shallow intermediate portion, said last mentioned portion having a substantially cylindrical recess therein, a plurality of diametrically opposed pairs of ratchet teeth formed integrally with said base and surrounding said recess, certain ofthe diametrically opposed ratchet teeth having fixed con-- tact elements superimposed thereon, a cylindrical molded insulating block rotatable within said recess, said block having a diametrical open slot extending inwardly rom the lower end thereof, said slot having an enlarged portion intermediate the ends thereof, a contactor loosely seated within said slot and having opposite end portions projecting from said block and adapted to overlie each pair of ratchet teeth selectively, said contactor having an enlargement to seat within the enlarged portion of said slot to restrain the former against endwise displacement, the other end of said block having ratchet teeth formed therein, a spindle integral with the last mentioned end of said block, a plate rotatable on said spindle and having integral inclined lugs adapted for driving engagement with said last mentioned ratchet teeth upon rotation of the former in one direction and to disengage said teeth upon rotation of said plate in the reverse direction, a pull chain and spring means for eflecting such movements'of said plate, means for adjusting the tension of the spring, said means comprising a plate rotatably and slidably supported on said spindle, spaced lugs-struck outwardly from said plate, and a bearing plate for said spindle having shoulders with which said lugs are adapted to engage.

4. In a rotary pull switch, in combination, a one-piece molded insulating base having approximately cylindrical end portions and a relatively shallow intermediate portion, said last mentioned portion having a substantially cylindrical recess therein, a plurality of diametrically opposed pairs of ratchet teeth formed integrally with said base and surrounding said recess, certain of the diametrically opposed ratchet teeth having fixed contact elements superimposed thereon, a cylindrical molded insulating block rotatable within said recess, said block having a diametrical open slot extending in wardly from the lower end thereof, said slot having an enlarged portion intermediate the ends thereof, a contactor loosely seated Within said slot and having opposite end portions projecting from said block and adapted to overlie each pair of ratchet teeth selectively, said contactor having an enlargement to seat within the enlarged portion of said slot to restrain the former against endwise displacement, the other end of said block having ratchet teeth formed therein,'a spindle integral with the last mentioned end of said block, a plate rotatable on said spindle and having integral inclined lugs adapted for driving engagement with said last mentioned ratchet teeth upon rotation of the former in one direction and to disengage said teeth upon rotation of said plate in the reverse direction, a pull chain and spring means for effecting such movements of said plate, means for adjusting the tension of the spring, said means comprising a plate rotatably and slidably supported on said spindle, spaced lugs struck outwardly from said plate, a

bearing plate for said spindle having shoulders with which said lugs are adapted to engage, one end portion of said insulating base having a plurality of radial notches formed therein at points spaced from the edge thereof, and a cup-shaped metallic supporting element having inwardly ofi'set lugs in interlocking engagement with said notches.

5. In a rotary pull switch, in combination, a one-piece molded insulating base having approximately cylindrical end portions and a relatively shallow intermediate portion, said last mentioned portion having a substantially cylindrical recess formed therein, a plurality of diametrically opposed pairs of ratchet teeth formed integrally with'said base and surrounding said recess, certain of the diametrically opposed ratchet teeth .having fixed contact elements superimposed thereon, a cylindrical molded insulating block rotatable within said recess, said block having a diametrical open slot extending inwardly from the lower end thereof, said slot having an enlarged portion intermediate the ends thereof, a contactor loosely seated within said slot and having opposite end portions projecting from said block and adapted to overlie each pair of ratchet teeth selectively, said contactor having an enlargement to seat within the enlarged portion of said slot to restrain the former against endwise displacement, the other end of said block having ratchet teeth formed therein, a spindle integral with the last mentioned end of said block, a plate rotatable on said spindle and having integral inclined lugs adapted for driving engagement with said last mentioned ratchet teeth upon rotation of the former in one direction and to disengage said teeth upon rotation of said plate in the re verse direction, a pull chain and spring means for effecting such movements of said plate, means for adjusting the tension of the spring, said means comprising a plate rotatably and slidably supported on said spindle, spaced lugs struck outwardly from said plate, a bearing plate for said spindle having shoul ders with which said lugs are adapted to engage, one end portion of said insulating base having a plurality of radial notches formed therein at points spaced from the edge thereof, and a cup-shaped metallic sup porting element having inwardly offset lugs in interlocking engagement with said notches, said supporting element having perforations and said insulating base having passages to provide clearance for the pull chain and the terminal wires of the switch.

6. In a device of the character described, in combination, a one-piece molded insulating base having approximately cylindrical end portions and an intermediate portion of seg- -mental form in cross section, pull switch mechanism located within said intermediate portion, a punched plate of insulating material bridging said end portions and adapted to retain the switch parts in assembled relation, center and screw shell lamp contacts secured to one of said end portions, and a cupshaped metallic support within which the other end portion is adapted to fit, said last mentioned end portion and said support having integral interlocking elements to prevent relative movement therebetween,.

7. Ina device of the character described, in combination, a one-piece molded insulating base having approximately cylindrical end portions and an intermediate portion of segmental form in cross section, pull switch mechanism located within said intermediate portion, a punched plate of insulating material bridging said 'end portions and adapted to retain the switch parts in assembled relation, center and screw shell lamp contacts socured to one of said end portions, and a cupshaped metallic support within which the other end portion is adapted to fit, said last mentioned end portion and said support havin integral interlocking elements to prevent re ative movement therebetween, certain of said elements having clamping engagement with one end of said insulating plate to retain the latter in position.

8. As an article of manufacture, a movable contact carrier for snap switches, said carrier consisting of a cylindrical block of molded insulating material, said block havin a dia-' metrical open slot extending inwar y from one end thereof, the other end of said block having a plurality of equally spaced inclined notches formed therein, the vertical end walls of two of said notches being alined with the longitudinal center line of'said slot, and a concentric spindle integral with said block and extending from the last mentioned end thereof.

9. In a device of the character described, the combination with a one-piece insulating base adapted for production by a straight line molding operation, said base comprising opposite end portions of substantially cylindrical contour and an intermediate portion of substantially segmental form in cross section, said intermediate portion and one of said end portions having perforations therethrough, a plurality of stationary contacts positioned on said base, and securing elements for said contacts, said elements penetratingsaid perforations in planes at substantially right angles to each other.

10. In a device of the character described, the combination with a one-piece insulating base adapted for production by a straight line molding operation, said base comprising opposite end portions of substantially cylindrical contour and an intermediate portion of substantially segmental form in cross section, said intermediate portion and one of said end portions having perforations therethrough, a plurality of stationary contacts positioned on said base, and securing elements for said contacts, said elements penetrating said perforations in planes at substantially right angles to each other, one of said perforations being formed b a slot extending inwardly from the perip iery of the last mentioned end portion at the junction of the latter with said intermediate portion.

11. In a device of the character described, in combination, a one-piece molded insulating base having approximately cylindrical end portions and an intermediate portion of segmental form in cross section, pull switch mechanism located within said intermediate portion, a punched plate of instulating mashaped metallic support within which theother end portion is adapted to fit, said last mentioned end portion and said support'having integral interlocking elements to prevent relative movement therebetween, and a tubular insulating member slidable over said insulating base to enclose said switch mechanism and said lamp contacts, said tubular member being adapted to rest upon the upper edge of said support.

12. In a pull chain lamp socket, in combination, a one-piece molded insulating base having substantially cylindrical end portions and an intermediate portion of segmental form in cross section, a cylindrical recess formed in said intermediate portion and ratchet teeth formed integrally with said base and surrounding said recess, a cylindrical molded insulating block rotatable within said recess, said block having a slot and a contactor of circular cross section engaged by the walls of said slot and retained thereby in engagement with said ratchet teeth, a rotary operating plate having ratcheting engagement with said block, a. pull chain for effecting rotation of said plate in one direction, a spring to bias said plate for rotation thereof in the reverse direction, a punched plate of insulating material bridging the end portions of the base and adapted to retain the aforementioned switch parts in assembled relation, center and screw shell lamp contacts superimposed upon one of the end portions of said base, a wiring terminal for said screw shell contact, a switch contact to be electrically connected with said center contact, and means penetrating said end portion of the base to secure all of said parts in assembled relation and to provide an electrical connection between said switch contact and said center contact.

13. In a pull chain lamp socket, in combination, a one-piece molded insulating base having substantially cylindrical end portions and an intermediate portion of segmental form in cross section. a cylindrical recess formed in said intermediate portion and ratchet teeth formed integrally with said base and surrounding said recess, a cylindrical molded insulating block rotatable within said recess,

said block having a slot and a contactor of circular cross section engaged by the walls of said slot and retained thereby in engagement with said ratchet teeth, a rotary operatin" plate having ratcheting engagement with sa-i d block, a pull chain for efi'ectlng rotation switch parts in assembled relation, center and screw shell lamp contacts superimposed upon one of the end portions of said base, a wiring terminal for said screw shell contact, a switch contact to be electrically connected with said center contact, means penetrating said end portion of the base to secure all of said parts in assembled relation and to provide. an electrical connection between said switch contact and said center contact, a second switch contact, a wiring terminal, means penetrating the intermediate portion of the base to secure said contact and terminal in position, a cup-shaped supporting member into which the lower end portion of said base is adapted to fit, said end portion having ledges formed in the periphery thereof and said supporting member having integral inbent portions engagin said ledges to hold said base and said mem er against movement relative to each other.

14;. A pull switch mechanism comprising, in combination, a one-piece molded insulating base having a substantially cylindrical recess formed therein and a plurality of diametrically opposed pairs of ratchet teeth formed integrally with said base and surrounding said recess, certain of said pairs of ratchet teeth having fixed contacts superimposed thereon, a contactor adapted to selectively bridge each pair of ratchet teeth, said contactor comprising a conductive rod of circular cross section having a peripheral enlargement intermediate the ends thereof, a molded insulating block of substantially cylindrical contour adapted for rotation within said recess, said block having a diametrical slot in the lower end thereof, the side walls of said slot being adapted to straddle said contactor for driving enga ement with the latter and said slot having s oulders for engagement by said enlargement of the contactor to prevent endwise displacement of the latter, said block having a plurality of inclined notches formed in the upper end thereof, an operating plate comprising a single sheet metal stamping having a plurality of integral lugs struck downwardly therefrom for driving engagement with the walls of said notches upon rotation of said plate in one direction, said lugs being arranged to disengage said notches upon rotation of said plate in the reverse direction, a forked lug integral with said plate and bent 15. A pull switch mechanism comprising,

in combination, a one-piece molded insulating base having a substantially cylindrical recess formed therein and a plurality of diametrically opposed pairs of ratchet teeth formed integrally with said base and surrounding said recess, certain of said pairs of ratchet teeth having fixed contacts superimposed thereon, a contactor adapted to se-' lectively bridge each pair of ratchet teeth, said contactor comprising a conductive rod of circular cross section having a peripheral enlargement intermediate the ends thereof, a molded insulating block of substantially cylindrical contour adapted for rotation within said recess, said block having a diametrical slot in the lower end thereof, the side walls of said slot being adapted to straddle said contactor for driving engagement with the latter and said slot having shoulders for engagement by said enlargement of the contactor to prevent endwise displacement of the latter, said block having a plurality of inclined notches formed in the upper end thereof, an operating plate com prising a single sheet metal stamping having a plurality of integral lugs struck downwardly therefrom for driving engagement with the walls of said notches upon rotation of said plate in one direction said lugs being arranged to disengage said notches upon r0- tation of said plate in the reverse direction, a forked lug integral with said plate and bent upwardly in a plane radial to the axial center of the latter, said lug being bent to hook form to provide a catch for the end ball of a chain, a second integral lug bent upwardly in a plane tangential to said plate, said last mentioned lug having the end portion thereof bent outwardly whereby the same is adapted to act as a guide rail for the chain, a

- torsion spring having a projecting end for engagement with said first mentioned lug, a tension adjusting plate having a. lu with Which the other end of said spring is a apted to engage, an abutment against which said adjusting plate is pressed by said spring, and cooperatively engaging parts on said abutment and said adjusting plate to retain the latter in any one of a number of adjusted positions.

16. In a switch mechanism, in combination, a movable contact carrier comprising a cylindrical block of molded insulatin material, said block having a diametrica passage therethrough, a contact rod of cylindrical cross section rotatably positioned within said passage and having its opposite end portions projecting from said block, the upper end of said block having a plurality of equally spaced notches formed therein, the bottom walls of said notches being inclined in a common direction, and a concentric spindle integral with said block and extending from said upper end thereof.

In witness whereof, I have hereunto subscribed my name.

WILLIAM C. TREGONING. 

